If you Contacts folder is enabled as an address book, it will appear
automatically.  The address book contains no data of its own.  It is just a
view of all the Contacts folders you have enabled as address books.

lets see if this works because it just worked for me; click the contacts tab
in the lower left part of outlook 2003 (mail,calendar,contacts,taksks). Now
that you're in the contacts section, go to the upper left part where it says
Contacts ("my contacts" is right under there). Right click the contacts icon
that you want to be added to address book and go to properties.  Click the
outlook address book tab, and click the check box that says "show this folder
as an e-mail address book". Your contacts should now show up in the "To..."
section of when you go to type a new email